Connection attempt to alternative access upon connection attempt rejection

ABSTRACT

The invention relates to methods, user equipments, computer programs, computer program products and carriers for access network selection between a first network and a second network. Said first and second networks comprise one or more access candidates. An access network selection procedure is performed for one or more access candidates of the second network, sequentially performing for the access candidates of the second network connection establishing attempts to one or more access candidates, by selecting a new access candidate from said one or more access candidates, and performing connection establishing attempts to said access candidate until a connection to the access candidate is established or a stop criterion for said access candidate is fulfilled.

TECHNICAL FIELD

The present technology relates to a method, a user equipment, acomputer, a computer program product and a carrier for performingconnection attempts to alternative access points and/or networks uponconnection attempt rejection.

BACKGROUND

Most current Wi-Fi or WLAN deployments are totally separate from mobilenetworks, and can be seen as non-integrated from the user equipment, UE,perspective. Most operating systems, OSs, for UEs such as Android™ andioS®, support a simple Wi-Fi offloading mechanism where a UE immediatelyswitches all its IP traffic to a Wi-Fi network upon a detection of asuitable network with a received signal strength above a certain level.Henceforth, the decision to offload to a Wi-Fi or not is referred to asaccess selection strategy and the term “Wi-Fi-if-coverage” is used torefer to the aforementioned strategy of selecting Wi-Fi whenever such anetwork is detected.

There are several drawbacks of the “Wi-Fi-if-coverage” strategyillustrated in FIG. 1. FIG. 1 illustrates examples of problems in FIGS.1a )-1 d) with “Wi-Fi-if-coverage” access network selection. Wi-Fiaccess selection today is performed by the UE with little considerationof radio performance, session/service continuity, load, mobility, etc.

Though the user/UE can save previous pass codes for already accessedWi-Fi Access Points, APs, hotspot login for previously non-accessed APsusually requires user intervention, either by entering the pass code inWi-Fi Connection Manager, CM, or using a web interface. The connectionmanager is software on a UE that is in charge of managing the networkconnections of the device, taking into account user preferences,operator preferences, network conditions, etc.

In FIGS. 1a-1d , a user equipment 10 has the possibility to connect toan AP of a mobile access network 20 or an AP of a Wi-Fi Access network30. The mobile access network 20 may operate according to the 3GPPand/or LTE standards.

In FIG. 1a , is also illustrated that the mobile access network isconnected to the Internet 60 via a backhaul network 40 and the Wi-Fiaccess network is connected to the Internet via a backhaul network 50.The backhaul network 40 of the mobile access network may in this exampleprovide a high rate fibre connection. The Wi-Fi access network offers anlow rate xDSL connection 50, e.g. 10/2 Mbps.

The UE may connect to the AP of either the mobile access network 20 viaa connection 25 offering 50 Mbps bandwidth, or the AP of the Wi-Fiaccess network 30 via a connection 35 offering a rate of 2 Mbps.

No consideration of expected user experience is made except thoseconsidered in the UE 10 implemented proprietary solution, and this canlead to a UE 10 being handed over from a high data rate mobile networkconnection 25 to a low data rate Wi-Fi connection 35. Even though theUE's OS or some high level software is smart enough to make the offloaddecisions only when the signal level on the Wi-Fi connection 35 isconsiderably better than the mobile network link 25, there can still belimitations on the backhaul 40 of the Wi-Fi AP 30 that may end up beingthe bottleneck.

FIG. 1b illustrates the situation when no consideration of the loadconditions in the mobile network 20 and Wi-Fi network 30 are made. Asillustrated, while the capacity of the Wi-Fi network 30 is full, themobile network 20 has low load and a lot of free capacity. As such, theUE might still be offloaded to a Wi-Fi AP that is serving several UEswhile the mobile network (e.g. LTE) that it was previously connected tois rather unloaded.

FIG. 1c illustrates the situation when interruptions of on-goingservices have occurred due to the change of IP address when the UEswitches to the Wi-Fi network 30. For example, a user who started aVoice over IP (VoIP) call while connected to a mobile network 20 islikely to experience a call drop when arriving home and the UE switchingto the Wi-Fi network automatically. Though some applications are smartenough to handle this and survive the IP address change (e.g. Spotify®),the majority of current applications do not. This places a lot of burdenon application developers if they have to ensure service continuity.

FIG. 1d illustrates the situation when no consideration of the UE's 10mobility along a path 15 is made. The dotted line of the oval area isindicating the coverage of the 3GPP/LTE mobile network 20, the dottedlines of the circles indicate the coverage areas of local Wi-Fi networkAPs 30. Due to this, a fast moving UE 10 can end up being offloaded to aWi-Fi AP 30 for a short duration, just to be handed over back to themobile network 20. This is specially a problem in scenarios like cafeswith open Wi-Fi, where a user walking by or even driving by the cafemight be affected by this. Such ping pong between the Wi-Fi and mobilenetwork can cause service interruptions as well as generate considerableunnecessary signalling (e.g. towards authentication servers)

Recently, Wi-Fi has been subject to increased interest from cellularnetwork operators, not only as an extension to fixed broadband access.The interest is mainly about using the Wi-Fi technology as an extension,or alternative to cellular radio access network technologies to handlethe always increasing wireless bandwidth demands. Cellular operatorsthat are currently serving mobile users with, e.g., any of the 3GPPtechnologies, LTE, UMTS/WCDMA, or GSM, see Wi-Fi as a wirelesstechnology that can provide good support in their regular cellularnetworks. The term “operator-controlled Wi-Fi” points to a Wi-Fideployment that on some level is integrated with a cellular networkoperators existing network and where the 3GPP radio access networks andthe Wi-Fi wireless access may even be connected to the same core networkand provide the same services.

There is currently quite intense activity in the area ofoperator-controlled Wi-Fi in several standardization organizations. In3GPP, activities to connect Wi-Fi access points to the 3GPP-specifiedcore network is pursued, and in Wi-Fi alliance, WFA, activities relatedto certification of Wi-Fi products are undertaken, which to some extentalso is driven from the need to make Wi-Fi a viable wireless technologyfor cellular operators to support high bandwidth offerings in theirnetworks. The term Wi-Fi offload is commonly used and points towardsthat cellular network operators seek means to offload traffic from theircellular networks to Wi-Fi, e.g., in peak-traffic-hours and insituations when the cellular network for one reason or another needs tobe off-loaded, e.g. to provide requested quality of service, maximizebandwidth or simply for coverage.

SUMMARY

One object of some of the provided techniques in this disclosure is tospecify UE behavior in reaction to rejection/disconnection from anaccess network.

According to one aspect of the following technique, a method andembodiments thereof are provided, wherein said method is a method inuser equipment for access network selection between a first network anda second network. Said first and second networks comprise one or moreaccess candidates. Said method comprise starting the access networkselection procedure for one or more access candidates of the secondnetwork, and sequentially performing for the access candidates of thesecond network connection establishing attempts to one or more accesscandidates by selecting a new access candidate from said one or moreaccess candidates, and performing connection establishing attempts tosaid access candidate until a connection to the access candidate isestablished or a stop criterion for said access candidate is fulfilled.

According to another aspect of the technique, a user equipment, UE, andembodiments thereof are provided, wherein said UE comprises a processorcircuitry and a computer program comprising computer program code which,when run in a processor circuitry causes the UE to perform the steps ofstarting the access network selection procedure for one or more accesscandidates of the second network, and sequentially performing for theaccess candidates of the second network connection establishing attemptsto one or more access candidates by selecting a new access candidatefrom said one or more access candidates, and performing connectionestablishing attempts to said access candidate until a connection to theaccess candidate is established or a stop criterion for said accesscandidate is fulfilled.

According to yet another aspect of the technique, a computer program andembodiments thereof are provided, wherein said computer programcomprises computer program code which, when run in a processor circuitryof a user equipment, UE, causes the UE to perform the steps of startingthe access network selection procedure for one or more access candidatesof the second network, and sequentially performing for the accesscandidates of the second network connection establishing attempts to oneor more access candidates by selecting a new access candidate from saidone or more access candidates, and performing connection establishingattempts to said access candidate until a connection to the accesscandidate is established or a stop criterion for said access candidateis fulfilled.

According to further one aspect of the technique, a computer programproduct and embodiments thereof are provided, wherein said computerprogram product comprises a computer program as defined above and acomputer readable means on which the computer program is stored. Saidcomputer program comprises computer program code which, when run in aprocessor circuitry of a user equipment, UE, causes the UE to performthe steps of starting the access network selection procedure for one ormore access candidates of the second network, and sequentiallyperforming for the access candidates of the second network connectionestablishing attempts to one or more access candidates by selecting anew access candidate from said one or more access candidates, andperforming connection establishing attempts to said access candidateuntil a connection to the access candidate is established or a stopcriterion for said access candidate is fulfilled.

According to further one aspect of the technique, a carrier andembodiments thereof are provided, wherein said carrier contains thecomputer program as defined above and the carrier is one of anelectronic signal, optical signal, radio signal or computer readablestorage medium. Said computer program comprises computer program codewhich, when run in a processor circuitry of a user equipment, UE, causesthe UE to perform the steps of starting the access network selectionprocedure for one or more access candidates of the second network, andsequentially performing for the access candidates of the second networkconnection establishing attempts to one or more access candidates byselecting a new access candidate from said one or more accesscandidates, and performing connection establishing attempts to saidaccess candidate until a connection to the access candidate isestablished or a stop criterion for said access candidate is fulfilled.

One advantage with the above proposed techniques is that a UE will nottry in vain to connect to an access node/network that it has beendisconnected/rejected from. Further, one advantage is that UE may try tofind the next best access node/network to connect to. Yet anotheradvantage is that the suggested techniques will improve UE batteryconsumption of the UE, avoid unnecessary network signalling load, andimprove the quality of experience of the user. It is also an advantagethat the above suggested techniques guarantee predictable and testableUE behaviour.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing, and other, objects, features and advantages of thepresent solutions will be more readily understood upon reading thefollowing detailed description in conjunction with the drawings inwhich:

FIGS. 1a-1d are block diagrams describing problems with prior artsolutions;

FIGS. 2, 3 and 4 are signalling schemes for illustrating differentsolutions for achieving final steering decisions to different accesscandidates, e.g. networks or access points of networks;

FIG. 5 is a flowchart of an embodiment of the method for access networkselection;

FIG. 6 is a flowchart of another embodiment of the method;

FIG. 7 is a flowchart of further one embodiment of the method;

FIG. 8 is a flowchart of yet another embodiment of the method;

FIG. 9 is a flowchart of an additional embodiment of the method;

FIG. 10 is a block diagram illustrating one example of a user equipment,wherein the method is implemented;

FIG. 11 is a block diagram illustrating another example of a userequipment, wherein the method is implemented.

DETAILED DESCRIPTION

In the following description, for purposes of explanation and notlimitation, specific details are set forth, such as particular circuits,circuit components, techniques, etc. in order to provide a thoroughunderstanding of the present solutions. However, it will be apparent toone skilled in the art that the present solutions may be practiced inother embodiments that depart from these specific details. In otherinstances, detailed descriptions of well-known methods, devices, andcircuits are omitted so as not to obscure the description of the presentsolutions with unnecessary detail.

The term “user equipment”, or abbreviated “UE”, will be used throughoutthis description for denoting a wireless communication device or anydevice which is capable of wireless communications. The term userequipment or UE may thus include any device, which may be used by a userfor wireless communications. Accordingly, the term user equipment or UEmay alternatively be referred to as a mobile terminal, a terminal, auser terminal (UT), a wireless terminal, a wireless communicationdevice, a wireless transmit/receive unit (WTRU), a mobile phone, a cellphone, a table computer, a smart phone, etc. Yet further, the term userequipment or UE includes MTC (Machine Type Communication) devices, whichdo not necessarily involve human interaction. MTC devices are sometimesreferred to as Machine-to-Machine (M2M) devices.

Following mechanisms provides the interworking of 3GPP and WLANnetworks.

The Access Network Discovery and Selection Function (ANDSF) contain datamanagement and control functionality necessary to provide networkdiscovery and selection assistance data as per operators' policy, seereferences [1], [2] and [3]. By supplying information about available3GPP and non-3GPP access networks to the UE, the ANDSF enables anenergy-efficient mechanism of network discovery, where the UE can avoidcontinuous and energy-consuming background scanning. Furthermore, theANDSF provides the mobile operators with a tool for the implementationof flexible and efficient UE steering of access mechanisms, where policycontrol can guide UEs to select one particular RAN over another andwhere certain traffic should be routed to.

In a roaming scenario, the UE can be provided policies from both theANDSF entities in the Home PLMN network (H-ANDSF) and the Visited PLMNnetwork (V-ANDSF). In case there are policy conflicts between the twopolicy sets, the policies coming from the H-ANDSF take precedence, seeref. [3]. It is also worth noting that user preferences take precedenceover both the H-ANDSF and V-ANDSF provided policies.

When communicating with the ANDSF server, the UE provides its locationand profile to the ANDSF server. The UE's location can be specified in3GPP cell IDs, 3GPP2 cell IDs, WiMAX cell IDs, WLAN SSIDs, or explicitgeographical location. The UE profile can contain detailed information,such as device capabilities and OS type, which can be used by the ANDSFserver to customize the ANDSF information to be sent to the UE. Theinformation sent to the UE basically falls into the category of accessnetwork discovery or/and operator policies for access selection.

Rel-12 3GPP RAN level integration that is able to provide more operatorcontrol, enhanced user experience and system performance/utilization isrequired as operator controlled WLAN deployments become more common andWLAN usage increases. In order to address this RAN level integration, astudy item, SI, was proposed in the 3GPP plenary meeting #58 thataddresses the issue of (operator deployed/controlled) WLAN and 3GPPinterworking at RAN level, see ref. [4]. The main aim of the SI was tofind solutions that address the under-utilization of operator deployedWLANs, sub-optimal UE performance while connected to WLAN and batterydrainage due to unnecessary WLAN scanning. Three solutions were proposedduring the study item phase as described in ref. [5], named solutions 1,2 and 3.

FIG. 2 is a signalling scheme illustrating solution 1, which is a UEbased solution, i.e. UE makes final steering decision, where the ANDSFis enhanced with additional policies that uses 3GPP RAN assistanceinformation provided to the UE through broadcast signalling, andoptionally dedicated signalling. If there are no ANDSF policies deployedor the UE doesn't support it, then an enhanced proprietaryWi-Fi-if-coverage mechanism is used. The main assistance informationprovided to the UE is the RAN load: percentage load, load levels (low,medium, high), offload preference indicator, etc. Additionally, oralternatively, information such as maximum expected resource allocationfor a UE on 3GPP, WLAN RSSI/BSS load thresholds, 3GPP RSRP/ReceivedSignal Code Power (RSCP) thresholds that have to be fulfilled fortraffic steering decisions.

The decisions are based on the RAN assistance information, UEmeasurements, information provided by WLAN and policies, or conditionsthat are obtained via ANDSF or via other Open Mobile Alliance DeviceManagement (OMA-DM) mechanisms or pre-configured at the UE to steertraffic to WLAN or to RAN. For example, ANDSF ISRP rules can be enhancedto utilize the RAN assistance and WLAN provided information:

-   -   If RAN RSRP is less than a threshold s and RAN direct load is        greater than a threshold x, and if WLAN RSSI is greater than a        threshold r and WLAN BSS load is less than a threshold y, move        flow to WLAN.    -   If RAN RSRP is greater than a threshold s′ and RAN direct load        is less than a threshold x′, and if WLAN RSSI is less than a        threshold r′ and WLAN BSS load is greater than a threshold y′,        move flow to UMTS/LTE.

The value of the thresholds (e.g. RAN RSRP/RSCP thresholds) may also beprovided by the ANDSF itself rather than included in the RAN assistanceinformation.

FIG. 3 is a signalling scheme illustrating solution 2, which followsprinciples similar to IDLE mode operations in 3GPP, where the UE followsRAN specified rules to perform cell (re-)selection. The RAN providesthrough dedicated and/or broadcast signalling thresholds which are usedin the rules.

Below are a couple of examples of RAN rules to be specified for solution2:

-   -   If measured_metric_A is less than a threshold1 and        measured_metric_B is greater than a threshold2, move flow to        WLAN.    -   If measured_metric_A is greater than a threshold3 and        measured_metric_B is less than a threshold4, move flow to 3GPP.

In the examples above threshold1 to threshold4 are part of theparameters that are communicated from the RAN, measured_metric_A tomeasured_metric_B are measurement values the UE has gathered and therules themselves are to be specified in RAN specifications. In additionsto the RAN rules, ANDSF rules can also be used, e.g. for flow basedtraffic steering via ISRP.

FIG. 4 is a signalling scheme illustrating solution 3, which followsprinciples similar to CONNECTED mode operations in 3GPP, where thefollowing three main steps are employed for traffic steering:

-   Step 1. Measurement control configuration: the RAN sends information    to the UE that includes details like the target WLAN(s) to be    measured, e.g. specific identities such as SSIDs/BSSIDs/HESSIDs or    more general information like operating frequencies,    events/thresholds for triggering measurement reports, e.g. when WLAN    signal becomes better/worse than a certain threshold, WLAN signal    becomes better/worse than a certain threshold and 3GPP signal    becomes worse/better than another threshold, etc.-   Step 2. Measurement reporting: When the conditions for triggering    thresholds, as configured in Step 1 above, are fulfilled, the UE    sends a measurement report to the 3GPP RAN.-   Step 3. Traffic steering: Based on the measurement report received    in Step 2, the RAN evaluates the received measurements and other    relevant information obtained in eNB/RNC and as a result of this    sends a traffic steering command to the UE, which can specify the    traffic to be steered. This can be explicit indication of each    bearer to be moved i.e. by specifying DRB/RB-IDs or more general    like the QoS Class Identifier (QCI), which can apply to many bearers    at once.-   Step 4. UE ACK/Response: In this step the UE indicates to the RAN    whether or not the action dictated by the traffic steering command    was successfully performed or not.

UEs in IDLE mode can request to setup an RRC connection for the sake ofsending measurement reports when the conditions of Step 1 are satisfied.Alternatively, solution 1 or 2, which are equally applicable to bothIDLE and CONNECTED UEs, might be employed for handling IDLE UEs whilesolution 3 is used only for CONNECTED UEs.

In the RAN #62 plenary meeting, a decision was made to go forward with awork item (WI) that proposes a solution that is a mixture of solution 1and 2, see ref. [6]. The objective of this work item is to specifymechanism for WLAN/3GPP access network selection and traffic steeringconsisting.

For the Access Network Selection part:

-   -   Selected RAN assistance parameters transferred via system        broadcast and/or dedicated signalling used within:        -   RAN rules defined within RAN WG specifications in case            enhanced ANDSF is not deployed in the network or not            supported by the UE.        -   ANDSF policies in case enhanced ANDSF is deployed in the            network and supported by the UE.    -   RAN assistance information may be enhanced with WLAN        identifiers, as described herein.

For the Traffic Routing part:

-   -   Selected RAN assistance parameters transferred via system        broadcast and/or dedicated signalling used within:        -   RAN rules specified in RAN2 WG specifications in case            enhanced ANDSF is not deployed or not supported by the UE.        -   ANDSF policies in case enhanced ANDSF is deployed in the            network and supported by the UE.    -   RAN assistance information may be enhanced with traffic routing        information (e.g. offload granularity) in case ANDSF is not        deployed or not supported by the UE.

It has in 3GPP been discussed different mechanisms for provisioning WLANidentifiers from the network to the UE which indicates to the UE whichWLANs should be considered in the WLAN interworking mechanism.

One example mechanism is that the 3GPP network broadcasts a set ofSSIDs/BSSIDs/HESSIDs/etc. The UE would then for the WLANs correspondingto the broadcasted identifier evaluate whether or not to connect to sucha WLAN. Other mechanisms which are based on dedicated signaling are alsopossible.

One problem to be solved is that the current behavior of the UE is notspecified when the UE can't connect to the access network prioritizedfor steering by ANDSF/RAN, e.g. UE gets rejected before admission to theaccess network and the UE gets disconnects during normal operations withthe access network, etc. For example, a UE might keep on trying to getconnected to the access network that just rejected it several timesbefore giving up, wasting UE battery, increasing network signaling load,and degrading the quality of experience of the user.

One object of some of the provided technique is to specify UE behaviorin reaction to rejection/disconnection from an access network. Insteadof repeatedly trying to reconnect to an access node/network that hasrejected/disconnected it, a UE will find the next best accessnode/network to connect with. It says herein that the UE connects ordisconnects from a WLAN. This may refer to that the UE connects ordisconnects from a certain WLAN access point, i.e. a BSS, identified bya BSSID, or from a set of WLAN access points, i.e. an ESS, identified byan ESSID or HESSID.

It herein is also described how the UE selects an alternative accessupon disconnection from a first access. It should be appreciated thatdisconnection here is not limited to the case when the UE has beenconnected to a WLAN and later gets disconnected, but the solutionspresented herein also covers the case when the UE has been rejected fromconnection to a WLAN e.g. during the connection attempt to that WLAN.Furthermore, the UE might have been disconnected because of genuineproblems in the network that do not account for deliberate steering,e.g. problem with credentials, loss of network connectivity,non-responding network nodes, etc.

It should also be appreciated that disconnection could also mean thattraffic has been rejected and cannot be steered to a certain WLAN. Forexample a UE gets admitted to connect to a network node but is rejectedto route traffic over that access.

When it herein says “connect to” it may mean one or more of the below:

Being “connected” to WLAN can mean different things, as exemplified bythe existence of one or more of the below conditions:

-   -   Connection could be establishing communication link between the        UE and the network node (or nodes), but not necessarily        transmitting information;    -   Connection could be establishing a new communication link (when        one was previously present, e.g. adding a “bearer”);    -   Connection could be establishing a communication link and        transmitting information over that communication link;    -   Connection could be starting to transmit information over a        communication link that was previously established;    -   802.11 Open-system authentication, OSA (Authentication to the        WLAN AP) has been completed or is under way;    -   802.1x EAP-SIM authentication (Authentication to the        AAA-servers) has been completed or is under way;    -   Four way hand-shake between the UE and the WLAN network has been        completed;    -   An IP address has been assigned to the UE in WLAN;    -   A PDN connection has been established through the WLAN network,        i.e., a connection between the UE and the PDN gateway;    -   Data traffic has been started through the WLAN network.

In the following, a technique for selection of access candidates, e.g.access networks, will be presented. Said technique controls the userequipment to avoid connecting to an access node/network that it has beendisconnected/rejected from. The following described technology enhancescurrent ANDSF or RAN procedures when a UE can't connect to the accessnetwork prioritized for steering, e.g. UE gets rejected before admissionto the access network, UE gets disconnects during normal operations withthe access network, etc.

FIG. 5 is a flowchart illustrating a method according one embodiment ofthe method for access network selection. The method may also beconsidered as a method for controlling connection attempts toalternative access candidates.

The method for access network selection is performed in a UE. Accordingto the following embodiment, the method comprises:

-   -   S110:—Starting the access network selection procedure for one or        more access candidates.    -   S120:—Sequentially performing for the access candidates of the        second network connection establishing attempts to one or more        access candidates by        -   selecting a new access candidate from said one or more            access candidates;        -   performing connection establishing attempts to said access            candidate until a connection to the access candidate is            established or a stop criterion for said access candidate is            fulfilled.

With new access candidate is meant an available alternative accesscandidate for which an attempt not has been performed. Different stopcriterions may be used in step S120 for stopping the access networkattempts, either alone or at the same time as a set of stop criteria.When one stop criterion of the set of stop criteria is fulfilled, theaccess network selection procedure for the access candidate isterminated.

According to one example, the stop criterion is that a rejection isreceived from the access candidate to which a connection establishingattempt is performed.

Another example of a stop criterion is based on a maximum time for aconnection establishing attempt, i.e. when the maximum time for aconnection establishing attempt to an access candidate is exceeded, theattempt is stopped. Said maximum time may be measured by a timer, whichis set and started when a connection establishing attempt is started foran access candidate. Said maximum time may be pre-set of a vendor oroperator. The maximum time may be per access network and/or node. It mayalso be so that there is one maximum time per group of access networks,e.g. one maximum time for accesses of a certain RAT. It may also be sothat the maximum time applies to a group of access networks and/or nodessuch as one maximum time for all WLANs with an SSID X. It would also bepossible that there is one maximum time applicable to all accessnetworks and/or nodes. The maximum time may be signalled from thenetwork to the terminal.

Yet another example of a stop criterion is based on a maximum number ofconnection establishing attempts for establishing connection to anaccess candidate, i.e. when the maximum number of connectionestablishing attempts to an access candidate is exceeded, the attempt isstopped. Said number of attempts is measured/counted by a counter means.Said maximum number may be pre-set of a vendor or operator.

When a user equipment terminal is disconnected from an access, the UEwill start, by step S110 in the method S100, connection attempts toalternative access candidates.

The UE terminal will upon disconnection from or rejection of connectionattempt to an access node/network A, apply a policy/rule to select analternative access candidate to connect to, e.g. node/network B. Thepolicy/rule that instructs the UE to connect to the alternative accesscandidate B may be the same as the policy/rule which instructed the UEto connect to the access node/network A.

The alternative access may be of the same Radio Access Technology (RAT)as the first access. For example a UE gets disconnected from a firstWLAN and then upon disconnection from that WLAN the UE connects toand/or steers traffic to a second WLAN.

The UE could be configured to consider a group of nodes in a network tobe the same access. For example, an operator may have a first WLAN A,which could have an ESSID identifier “A”, comprising three nodes; WLANAP 1, WLAN AP 2 and WLAN AP 3, which could have a BSSIDs “1”, “2” and“3”, respectively, and a second WLAN B, which could have an ESSIDidentifier “B”, comprising two nodes; WLAN AP 4 and WLAN AP 5, whichcould have a BSSIDs “4”, and “5”, respectively. According to thisembodiment the UE can consider all the nodes of WLAN A to be one access,for example due to that they share the same ESSID, and all the nodes ofWLAN B to be one access, for example due to that they share the sameESSID. Hence, according to some embodiments herein, if the UE getsdisconnected from a node in WLAN A the UE would select WLAN B andconnect to a node in WLAN B.

The UE could be configured to consider each node of a network to bedifferent accesses, e.g. in the example above with WLAN A and WLAN Bthere would be in total 5 accesses; WLAN 1, WLAN 2, WLAN 3, WLAN 4 andWLAN 5. And according to some embodiments herein the UE could, upondisconnection from WLAN 1, select WLAN 2 to attempt to connect to, eventhough the ESSID for WLAN 1 and WLAN 2 is the same.

It would also be possible that the alternative access is of anotherRadio Access Technology compared to the first access. For example, a UEgets disconnected from a WLAN and then connects to and/or steers trafficto a 3GPP network.

For alternative access selection in step S120 different criteria may beused. In some embodiments the UE will select an alternative access giventhat the first access has indicated to the UE a certain cause value forthe disconnection from the first access, while another cause value, orabsence of cause value indication the UE would apply a default behavior,where the default behavior could be based on UE implementation and, asexplained earlier, may be that the UE is reattempting to connect to thefirst access.

In one realization of this embodiment, a WLAN network indicates to theUE a cause value X at, or before, the disconnection of the UE. The UEwill when being disconnected from the WLAN select alternative access,e.g. another WLAN or an access implementing another Radio AccessTechnology (RAT) such as a 3GPP RAT, and connect to that other access.However if the network indicates another cause value, e.g. cause valueY, or not providing any cause value, the UE would apply the defaultbehavior which, as explained earlier, may be to try to reconnect to thefirst access candidate. The benefit of this embodiment is that the WLANaccess can decide whether the UE should connect to an alternative accessor apply some other behavior.

Different selection mechanisms for the alternative access can be appliedin conjunction with the above embodiments of the method S100. Hereafter, a few example mechanisms are described.

The UE may select the alternative access candidate based on a priorityorder associated with alternative accesses. This priority order may beindicated by a network node, for example in an ANDSF policy, asdescribed above or some other mechanism such as the RAN mechanismdescribed above.

In one possible implementation of this embodiment the method S100 and aUE will upon disconnection, or rejection, from the first accesscandidate evaluate which access has second highest priority and thenevaluate whether that access is available or not. Whether an access isavailable or not may be determined based on for example an ANDSF policyor some other mechanism such as the RAN mechanism described above. Ifthe second highest priority access is available the UE would attempt toconnect to that access, otherwise the UE would refrain from connectingto that access and evaluate which is the third highest priority accessand whether the third highest priority access is available or not, andso on.

Regarding the access network selection procedure S100 in general: Saythe UE has ANDSF rules or RAN policies that control the UE on how to dothe access network selection. These policies/rules are always active inthe UE. The embodiments proposed of the method S100 are just concerningonce those policies/rules have fired, and on how to proceed. Example: aRAN rule that says if RSRP <x and there is a WLAN with RSSI >y, thenconnect to it. Also WLAN A, B, C . . . are listed according todecreasing priority (i.e. A is the most preferred). So at time x1: UEnotices that it is in the coverage of WLANs belonging to A and C, andthey fulfil the criteria, attempts to connect to A but gets rejected,then tries C, gets connected. 2 minutes after that, the UE notices thatit is in the coverage of WLANs B and C. It is already connected to C butsince B is of higher priority than C, it tries to connect to B.

FIG. 6 is a flowchart illustrating a method according another embodimentof the method. As illustrated in the flowchart of this embodiment, themethod may comprise a terminating step, which is optional.

The method S100 for access network selection procedure is performed in aUE. According to the following embodiment, the method comprises:

-   -   S110:—Starting the access network selection procedure for one or        more access candidates;    -   S120:—Sequentially performing for the access candidates of the        second network connection establishing attempts to one or more        access candidates by        -   selecting a new access candidate from said one or more            access candidates;        -   performing connection establishing attempts to said access            candidate until a connection to the access candidate is            established or a stop criterion for said access candidate is            fulfilled.

The method S100 comprises the optional terminating step, as illustrated:

-   -   S130:—Terminating access network selection procedure if        connection to one of said one or more access candidates is        established or each connection establishing attempt for all        access candidates have been stopped by a stop criterion.        -   FIG. 7 is a flowchart illustrating an embodiment of the            method. In this embodiment of the method, the performing            step S120 involves:    -   S121:—A new access candidate available? With new access        candidate is meant an available access candidate for which an        attempt not has been performed. If any new access candidate is        not available, test criterion is not fulfilled, “NO”, because        all candidates have been tested without any connection being        established. The process is then returned to S110, waiting for        starting the access network selection procedure again. The        process may be stopped in the terminating step, S130, if used in        the embodiment, see FIG. 8 below. If a new access candidate is        available, test criterion is fulfilled, “YES”, and steps S122        and S123 are performed.    -   S122:—Selecting a new access candidate from said one or more        access candidates.    -   S123:—Start connection establishing attempt to said access        candidate. A connection establishing attempt may comprise one or        more attempts to establish connection to the access candidate.        When the connection establishing attempt has started, the        procedure comprises a test, or check, step S124, wherein        connection establishing attempts to said access candidate is        performed until a connection to the is established or a stop        criterion for said access candidate is fulfilled;    -   S124:—Connection to access candidate established or stop        criterion fulfilled?

As soon as the criterion in S124 is fulfilled, YES, the attempt isstopped, The UE can use the established connection for sending andreceiving signalling and data communication. As long as the criterion isnot fulfilled, NO, the attempt/-s for the selected candidate is/arecontinuing if not one “stop criteria is fulfilled”, which results inthat the process leaves the test, S124, for step S121 for checking if anew access candidate is available, and if so, selecting a new candidate,S122, and restart the connection attempts, S123.

FIG. 8 is a flowchart illustrating an embodiment comprising thetermination step, S130, of the method S100. The embodiment operates asthe embodiment described above in FIG. 7, but if a new access candidateis not available, in test criterion in S121 is not fulfilled, “NO”,because all candidates have been tested without any connection beingestablished. The process is than stopped in the terminating step, S130.

FIG. 9 is a flowchart illustrating an additional embodiment comprisingthe termination step, S130, of the method S100.

The method S100 starts when the UE is e.g. disconnected from the firstnetwork, and starts the access network selection procedure for one ormore alternative access candidates, S110. When the method starts, thereare usually a number of access candidates available. Whether, or not,there is one or more access candidate is tested in S121:

-   -   S121:—A new access candidate available? If any new access        candidate is not available, test criterion is not fulfilled,        “NO”, because all candidates have been tested without any        connection being established. The process is stopped directly in        the terminating step, S130. If a new access candidate is        available, test criterion is fulfilled, “YES”, and step S122 is        performed.    -   S122:—Selecting a new access candidate from said one or more        access candidates. When a new access candidate is selected, e.g.        due to a priority order and/or a cause value, step S124 is        performed. Said step S124 involves three steps S124A, S124B, and        S124C, constituting an inner access candidate connection        establishing attempt loop, which now will be described.    -   S124A:—Perform connection establishing attempt to said access        candidate. A connection establishing attempt may comprise one or        more attempts to establish connection to the access candidate.        When the connection establishing attempt has started, the        procedure comprises a test, or check, step S124B:    -   Connection established? If the connection establishing attempts        to said access candidate is successful, YES, a connection to the        access candidate is established, and the method S100 is        terminated in the terminating step, S130. However, if a stop        criterion is reached in S124C, e.g. the number of attempts is        exceeding the maximum number of attempts allowed, the method        S100 is continuing by checking for a new access candidate, and        if available, as confirmed by the test S121, a new access        candidate is selected for the connection attempts. The method        S100 is performed until a connection to the UE is established,        YES, or a stop criterion for said access candidate is reached in        S124C.

Regarding the selecting of a new access candidate from said one or moreaccess candidates as in S120, i.e. step S122 in step S120. Differentmechanisms or techniques for selecting alternative, or new, accesscandidates are hereafter exemplified. One such mechanism are to use apriority order of the access candidates.

-   -   a) The UE evaluates which of the access candidates available        that has the highest priority. Consider for example a case where        a UE has four access candidates, e.g. WLAN accesses, which        should be considered and currently the UE is connected to one of        these WLAN accesses. The UE could then, according to this        mechanism, upon disconnection from, or upon connection attempt        rejection from the WLAN the UE is currently connected to,        evaluate which of the other three WLAN accesses has the highest        priority and for that access candidate determine whether the        access is available or not. If that WLAN is available the UE        would attempt to connect to that access candidate, otherwise the        UE would determine which of the other two access candidates has        highest priority and then evaluate whether that access candidate        is available or not. If that access candidate is available the        UE would attempt to connect to that access otherwise the UE        would evaluate whether the fourth access candidate is available        and connect to that fourth access if available.    -   b) A priority list of available access candidates. In another        possible implementation of this embodiment the UE will maintain        a priority list of available access candidates. I.e. the UE will        propagate the priority list only with access candidates which        are available. The UE may evaluate for all considered access        candidates whether they are available or not and then keep in        the list only those access candidates which are available. This        availability evaluation procedure may be done periodically and        hence list of available accesses, i.e. access candidates, would        be kept up-to-date in the sense that all lists in this list are        considered available. In addition to or as an alternative to        that, the UE may update the priority list when it gets        rejected/disconnected with a specific cause value.

Consider for example a case where the UE has four WLAN accesses whichshould be considered; WLAN A, WLAN B, WLAN C and WLAN D. The UE wouldthen evaluate for these access candidates which are considered availableand which are not considered available. It may be so that only WLAN A,WLAN C and WLAN D are considered available and hence the list ofavailable WLANs would only contain these three WLANs. If for example theUE is initially connected to (or is trying to connect to) WLAN A butthen gets disconnected from (or is rejected from connecting to) WLAN Athe UE would select one of the other WLANs. The UE may select out ofthose WLANs in the list of available WLANs the WLAN which has thehighest priority.

Note that in the examples above, the candidate target list containedonly WLANs. That is just for the sake of brevity, and the list candidatetarget can contain accesses belonging to other RATs as well.

The above described methods and embodiments thereof may be implementedin digital electronically circuitry, or in computer hardware, firmware,software, or in combinations of them. Devices, means, circuitry or unitsmay be implemented in a computer program product tangibly embodied in amachine readable storage device for execution by a programmableprocessor; and method steps described above may be performed by aprogrammable processor executing a program of instructions to performfunctions achieved by the method and embodiments thereof by operating oninput data and generating output.

The described techniques may advantageously be implemented in one ormore computer programs that are executable on a programmable systemincluding at least one programmable processor, processing circuitry,processing means, etc. coupled to receive data and instructions from,and to transmit data and instructions to, a data storage system, atleast one input device, and at least one output device. Each computerprogram may be implemented in a high-level procedural or object-orientedprogramming language or in assembly or machine language if desired; andin any case, the language may be a compiled or interpreted language.

Generally, a processor, processor unit, processing circuitry, processingmeans, etc., will receive instructions and data from a read-only memoryand/or a random access memory. Storage devices, such as computerreadable means or computer readable storage medium, suitable fortangibly embodying computer program instructions and data include allforms of non-volatile memory, including by way of example semiconductormemory devices, such as EPROM (erasable programmable read only memory),EEPROM (electrically erasable programmable read only memory), and flashmemory devices; magnetic disks such internal hard disks and removabledisks; magneto-optical disks; and CD-ROM (Compact Disc Read-Only Memory)disks. Any of the foregoing may be supplemented by, or incorporated in,specially-designed ASICs (Application Specific Integrated Circuits).

FIGS. 10 and 11 are block schemes illustrating embodiments of a UE forimplementing the above described method and its embodiments.

FIG. 10 is a block diagram illustrating one example of a UE 200,preferably a UE for communicating with a radio node 250 in acommunications network, e.g. wireless communications network ortelecommunications network supporting Wi-Fi by means of a WLAN 250B,250C or any RAT by means of a RAN 250A. Thus, different accesscandidates exist for performing connection establishing attempts towardsand to establish a connection 222 over an air interface. Said UE 200 isconfigured to perform connection establishing attempts. The UE comprisesat least one processing circuitry 210 comprising a processor unit 212and a memory storage 214. The UE 200 further comprises an interface 220for enabling input and output communication 222 with other nodes, etc.The UE 200 may also comprise computer readable means or computerreadable storage medium 230 on which a computer program is stored. Saidmeans or medium 230 may be fixed in the UE or removable.

It is understood that said UE may comprise a different number ofcomputer readable means or computer readable storage medium 230, and theillustrated number of computer readable means or computer readablestorage medium 230 only is for illustrative purposes. One or several ofthe computer readable means or computer readable storage medium 230 maybe physically separated from the other computer readable means orcomputer readable storage medium 230, or may reside on the same physicalmedia.

Said processing circuitry 210 causes the UE to perform the steps of theabove described method S100 and embodiments thereof. Thus, theprocessing circuitry 210 of the UE 200 is adapted to and operative tostart an access network selection procedure for one or more accesscandidates, sequentially perform connection establishing attempts forthe access candidates of the second network to one or more of the accesscandidates. Said processing circuitry 210 may also cause the UE toperform the step of terminating the access network selection procedureif connection to one of said one or more access candidates isestablished or each connection establishing attempt for all accesscandidates have been stopped by a stop criterion.

The stop criterion may be that a rejection is received from the accesscandidate to which a connection establishing attempt is performed,and/or a maximum time for a connection establishing attempt, and/or amaximum number of connection establishing attempts for establishingconnection to an access candidate.

The UE 200 may be adapted, e.g. by means of the processing circuitry 210to select a new access candidate from said one or more access candidate,to start a connection establishing attempt to said access candidate, tocheck if connection to an access candidate is established, and to checkif a stop criterion is fulfilled.

The above mentioned embodiments may be implemented as processingcircuitry 210 and a computer program comprising computer program codewhich, when run in a processor circuitry of a UE, causes the UE toperform the method steps of the method S100:

-   S110:—Starting the access network selection procedure for one or    more access candidates;-   S120:—Sequentially performing for the access candidates of the    second network connection establishing attempts to one or more    access candidates by    -   selecting a new access candidate from said one or more access        candidates;    -   performing connection establishing attempts to said access        candidate until a connection to the access candidate is        established or a stop criterion for said access candidate is        fulfilled; and optionally in some embodiments,-   S130:—Terminating access network selection procedure if connection    to one of said one or more access candidates is established or each    connection establishing attempt for all access candidates have been    stopped by a stop criterion.

The computer program comprises computer program code which, when run ina processor circuitry of a node, causes the node to perform thedifferent embodiments of the method S100, as described above.

It is further provided a computer program product comprising saidcomputer program and a computer readable means on which the computerprogram is stored.

It is further provided a carrier containing the computer program,wherein the carrier is one of an electronic signal, optical signal,radio signal or computer readable storage medium.

FIG. 11 is a block diagram illustrating another example of oneembodiment of a UE 200, preferably a UE for communicating with a radionode 250 in a communications network, e.g. wireless communicationsnetwork or telecommunications network supporting Wi-Fi by means of aWLAN 250B, 250C or any RAT by means of a RAN 250A. Thus, differentaccess candidates exist for performing connection establishing attemptstowards and to establish a connection 222 over an air interface.

The above mentioned embodiments of the method S100 may be implemented asmodules of a UE 200, said modules causes the UE to perform the methodsteps of the method S100.

The UE may therefore comprise a first module S110 for starting theaccess network selection procedure for one or more access candidates, asecond module S120 for sequentially performing for the access candidatesof the second network connection establishing attempts to one or moreaccess candidates, and a third module S130 for terminating the accessnetwork selection procedure if connection to one of said one or moreaccess candidates is established or each connection establishing attemptfor all access candidates have been stopped by a stop criterion.

The UE 200 may comprise further modules for implementing the differentembodiments of the method S100, said modules causes the UE to performthe different embodiments of the method S100. E.g. the UE 200 maycomprise a counter means for enabling a stop criterion which is based ona maximum number of connection establishing attempts for establishingconnection to an access candidate, i.e. when the maximum number ofconnection establishing attempts to an access candidate is exceeded, theattempt is stopped. Said number of attempts is measured/counted by thecounter means. Another example is for enabling a stop criterion which isbased on a maximum time for a connection establishing attempt, i.e. whenthe maximum time for a connection establishing attempt to an accesscandidate is exceeded, the attempt is stopped. Said maximum time may bemeasured by a timer, which is set and started when a connectionestablishing attempt is started for an access candidate. The userequipment may comprise a module for handling stop criterion received,e.g. at a rejection from the access candidate to which a connectionestablishing attempt is performed. The user equipment may comprise amodule for handling cause values e.g. in a received rejection, saidcause value indicating an alternative access candidate for the userequipment to select. The cause value may also indicate selection of analternative access candidate implementing a Radio Access Technologywhich differs from the Radio Access Technology used in the firstnetwork. The user equipment may also be adapted to at an absence of adefault value, or the cause value is indicating for the user equipment,to perform a default behaviour.

The user equipment may further comprise a module for selecting onealternative access candidate based on a priority order. The UE may beadapted to evaluate which of the access candidates available has thehighest priority.

The user equipment may further comprise a module for maintaining thepriority list with a list of available access candidates. Said list ofavailable access candidates may be updated, e.g. at rejection ordisconnection with a specific cause value.

The modules described above with reference to FIGS. 10 and 11 may beconsidered as logical units, and do not necessarily correspond toseparate physical units or modules. Thus, the person skilled in the artwould appreciate that the units disclosed in the FIGS. 10 and 11 may beimplemented as physically integrated units, and/or physically separateunits, and that the units are provided with appropriate processingcircuits.

Modifications and other variants of the described embodiment(s) willcome to mind to one skilled in the art having the benefit of theteachings presented in the foregoing descriptions and the associateddrawings. Therefore, it is to be understood that the embodiment(s)is/are not to be limited to the specific examples disclosed and thatmodifications and other variants are intended to be included within thescope of this disclosure. Although specific terms may be employedherein, they are used in a generic and descriptive sense only and notfor purposes of limitation.

A number of embodiments of the described method and UE have beendescribed. It will be understood that various modifications may be madewithout departing from the scope of the following claims. Therefore,other implementations are within the scope of the following claims.

ABBREVIATION LIST

-   WLAN Wireless Local Area Network-   PDN Public Data Network-   3GPP Third Generation Partnership Project-   LTE Long Term Evolution-   UMTS Universal Mobile Telecommunications System-   WCDMA Wideband Code Division Multiple Access-   GSM Global System for Mobile Communications-   PLMN Public Land Mobile Network-   RAN Radio Access Network-   RAN WG Radio Access Network Working Group-   RAT Radio Access Technology-   IP Internet Protocol-   eNB base (transceiver) station in LTE systems-   RNC Radio Network Control-   RRC Radio Resource Control-   AP Access Point-   BSS Basic Service Set-   ESS Extended Service Set-   SSID Service Set IDentification-   BSSID Basic Service Set IDentification-   HESSID Homogenous Extended Service Set IDentification-   RSSI Received Signal Strength Indicator-   ISRP Inter System Routing Policy-   RSRP Reference Signal Received Power-   DRB Data and Signalling Radio Bearers-   RB-ID Radio Bearer IDentification-   EAP-SIM Extensible Authentication Protocol Subscriber Identity    Module-   AAA Authentication, Authorization and Accounting

REFERENCE LIST

-   [1] 3GPP TS 23.402, Architecture enhancements for non-3GPP accesses.-   [2] 3GPP TS 24.312, Access Network Discovery and Selection Function    (ANDSF) Management Object (MO)-   [3] 3GPP TS 24.302, Access to the 3GPP Evolved Packet Core (EPC) via    non-3GPP access networks; Stage 3-   [4] RP-122038—New Study Item Proposal on WLAN/3GPP Radio    Interworking, Intel Corporation-   [5] 3GPP TR 37.834: WLAN/3GPP Radio Interworking-   [6] 3GPP RP-132101, New Work Item Proposal on WLAN/3GPP Radio    Interworking

1-18. (canceled)
 19. A user equipment, UE, comprising: processorcircuitry, and memory containing computer program code which, when runin the processor circuitry, causes the UE to perform a method for accessnetwork selection between a first network and a second network, each ofsaid first and second networks comprising one or more access candidates,the method comprising: starting an access network selection procedurefor one or more access candidates of the second network; andsequentially performing, for the one or more access candidates of thesecond network, connection establishing attempts to the one or moreaccess candidates by: selecting a new access candidate from said one ormore access candidates; and performing connection establishing attemptsto said access candidate until a connection to the access candidate isestablished or a stop criterion for said access candidate is fulfilled.20. The user equipment according to claim 19, wherein the methodperformed by the user equipment further comprises: terminating theaccess network selection procedure if connection to one of said one ormore access candidates is established or each connection establishingattempt for all of the one or more access candidates of the secondnetwork has been stopped by a stop criterion.
 21. The user equipmentaccording to claim 19, wherein the stop criterion is based on a maximumtime for a connection establishing attempt.
 22. The user equipmentaccording to claim 19, wherein the stop criterion is based on a maximumnumber of connection establishing attempts for establishing connectionto an access candidate.
 23. The user equipment according to claim 19,wherein the stop criterion is that a rejection is received from theaccess candidate to which a connection establishing attempt isperformed.
 24. The user equipment according to claim 19, wherein theselecting is based on a cause value indicating an alternative accesscandidate for the user equipment to select.
 25. The user equipmentaccording to claim 24, wherein the cause value indicates selecting analternative access candidate implementing a Radio Access Technologywhich differs from the Radio Access Technology used in the firstnetwork.
 26. The user equipment according to claim 24, wherein anabsence of a default value or the cause value is indicating for the userequipment to perform a default behaviour.
 27. The user equipmentaccording to claim 19, wherein the user equipment selects onealternative access candidate based on a priority order.
 28. The userequipment according to claim 27, wherein the UE is adapted to evaluatewhich of the access candidates available that has the highest priority.29. The user equipment according to claim 27, wherein the user equipmentis adapted to maintain a priority list with a list of available accesscandidates.
 30. The user equipment according to 29, wherein the userequipment is adapted to update said list of available access candidates.31. The user equipment according to claim 29, wherein the user equipmentis adapted to update said list of available access candidates when theuser equipment gets rejected or disconnected with a specific causevalue.
 32. The user equipment according to claim 19, wherein the secondnetwork implements a different Radio Access Technology than the RadioAccess Technology of the first network.
 33. (canceled)